1. Field of the Invention
The present invention relates generally to display of three-dimensional (3D) image/video. More particularly, the present invention relates to an apparatus and method for displaying a stereoscopic 3D image/video based on Lightweight Application Scene Representation (LASeR).
2. Description of the Related Art
Various technologies are now under consideration for providing multimedia services. In particular, one technology that provides temporal, spatial configuration and representation of elements of multimedia content is the Moving Picture Experts Group (MPEG)-4 Lightweight Application Scene Representation (LASeR). LASeR is a multimedia content format that allows users to enjoy multimedia services in a communication environment in which available resources are insufficient, for example in the mobile terminal environment. More specifically, LASeR is a technology proposed for free representation of various multimedia and interaction with users, using such data as scene description, video, audio, image, font, text, metadata and script. The LASeR data is composed of an Access Unit (AU) that includes at least one command, wherein the command is used for changing a scene property at a particular time. The commands, which should be simultaneously executed, are included in one AU as one bundle. The AU can be one scene, sound, or short animation. Currently, LASeR is under standardization for convergence with the World Wide Web Consortium (W3C) and uses the Scalable Vector Graphics (SVG) and Synchronized Multimedia Integration Language (SMIL) standards of W3C. Using SVG allows for displaying the same picture quality regardless of the type of screen or resolution since it represents (expresses) scenes in a mathematical manner. Also, effective representation of scenes is possible with low data capacity since it is based on text. SMIL defines and shows a temporal, spatial relation of multimedia data. The use of SVG and SMIL can represent audio, video, text, image, video, polyhedron, etc.
FIG. 1 is a diagram illustrating an operation of a terminal that received LASeR content according to the conventional art. Herein, the term “LASeR content” refers to the resource elements displayed in a scene actually being serviced in the terminal, including media such as video and audio. Referring to FIG. 1, the terminal receives a LASeR service in step 100. The terminal decodes LASeR content of the received LASeR service in step 110. In step 120, the terminal checks LASeR commands from the decoded LASeR content and executes the LASeR commands. The terminal processes all events of the LASeR content in step 130, and determines in step 140 active a media object according to time information of the media object. Finally, in step 150, the terminal renders and displays scene components, including media such as video and audio. The operation of the terminal that received the LASeR content follows the Execution Model of the ISO/IEC 14496-20 MPEG-4 LASeR standard document, the entire disclosure of which is hereby incorporated by reference. The above-described LASeR content can be represented in the syntax of Table 1 using a LASeR language. According to Table 1, the terminal configures (describes) and displays scenes (<svg> . . . </svg>) included in a corresponding LASeR command every time the LASeR command (<NewScene>) is executed.
TABLE 1<NewScene>   <svg width=“480” height=“360” viewBox=“0 0 480 360”>   ...   </svg></NewScene>
With regard to recent image/video technology, intensive research is being conducted on a scheme of realizing three-dimensional (3D) image/video that provides a more-realistic image/video presentation. One method for realizing 3D image/video is to extract a 3D object from several cuts of an image/video at various angles using several cameras. However, this is a complex method that requires correspondingly complex calculations. Therefore, many attempts are being made on a method for projecting the left-visual point image/video and the right-visual point image/video to their corresponding positions on the existing display device to exploit the human eye's visual perception characteristic. That is, the left- and right-visual point image/videos are projected to their corresponding positions and then the left visual point and the right visual point are separately imaged on the left eye and the right eye of the user, thereby providing a stereoscopic effect. The 3D image/video made using the inter-eye visual difference method is called ‘stereoscopic 3D image/video’.
As interest in 3D image/video increases, portable terminals having a Barrier Liquid Crystal Display (LCD) that can reproduce stereoscopic content and provide more-realistic image/video to the user are being advanced. In particular, since the method for reproducing stereoscopic content can represent rich scenes while requiring less data capacity by using various elements, many service providers intend to select and provide LASeR as a scene representation tool.
A stereoscopic video stream should contain the left and right image/video data together and is therefore different from a normal video stream such as the video stream illustrated in FIG. 2A. Referring to FIG. 2A, it can be noted that the normal video stream is composed of one stream in which a plurality of image/video frames are concatenated.
FIGS. 2B to 2E are diagrams illustrating conventional stereoscopic video streams. The stereoscopic video stream of FIG. 2B is composed of one video stream in which the left and right images/videos are contained in one frame together. The stereoscopic video stream of FIG. 2C is composed of one video stream in which the left and right images/videos are contained in one frame line by line in an interleaving manner. The stereoscopic video stream of FIG. 2D is composed of one video stream in which the left and right image/video frames alternately occur, and the stereoscopic video stream of FIG. 2E is composed of independent left and right image/video streams.
As illustrated in FIGS. 2B to 2E, in the stereoscopic 3D image/video video stream, unlike in the conventional video stream, even though the left and right images/videos are configured in two video streams or one video stream, the left and right images/videos are separately configured in their associated frames, or configured in one frame in a mixed manner.
Regarding the stereoscopic 3D image/video, both the left and right images/videos are mixed and displayed as a single 3D image/video according to the LCD Barrier type of display. However, since the existing LASeR-based terminal recognizes and displays only one video stream for one media element, in the case where it is desired to display the stereoscopic 3D image/video, if two or more video streams are delivered, as shown by reference numeral 210 of FIG. 2E, it is not possible to identify the video stream that should be displayed. Otherwise, as the terminal displays only one recognizable video stream among the two or more video streams, it cannot display 3D image/video. In addition, even if the left and right images/videos are delivered on one video stream as shown in FIGS. 2B to 2D, they are not displayed as 3D images/videos made by mixing both the left and right images/videos as shown by reference numeral 200 of FIG. 2D. Rather, a normal image/video is displayed in which the left and right images/videos alternately occur. Such display is likely to make the user feel fatigued. Further, in the case of FIG. 2B, since the user should view almost the same left and right images/videos separately on one screen, the size of videos is unnecessarily reduced from the viewpoint of the user, and the user is also apt to feeling fatigued. Even in the case of FIG. 2C, the distorted images/videos are viewed, causing the same problems as the other examples. Therefore, when there is an intention to provide stereoscopic 3D image/video, there is a demand for a method and apparatus for providing stereoscopic 3D image/video on a LASeR-based terminal.
In addition, there is a demand for a function capable of parsing information on stereoscopic 3D image/video and delivering the optimized image/video to a LASeR engine regardless of whether it supports stereoscopic 3D image/video of a LASeR engine mounted in the terminal.